Electron discharge device



Nov. 25, 1958 c. F. MILLER ELECTRON DISCHARGE DEVICE Filed July 31. 1956 INVENTOR Carl F. Miller. %BY

ATTORNEY States Patent ELECTRON DISCHARGE DEVICE Application July 31, 1956, Serial No. 601,277

6 Claims. (Cl. 313-261) This invention relates to electron discharge devices and, more particularly, to electron discharge devices having electrode structures that have low noise and microphonic characteristics and that are particularly suited for automatic or mechanized assembly.

Electron discharge devices are usually constructed with electrode elements being held in the apertures of spacer members. Therefore, the electrode elements are frequently slightly loose after assembly which gives rise to noise and microphonics during operation. Also, when the electrode elements are threaded into the apertures of the spacer members, additional distortion may result. In addition, these electrode structures are, as a rule, unsuitable for use in automatic or mechanized assembly techniques.

Accordingly, it is an object of my invention to provide an improved electrode structure for an electron discharge device which has improved noise and microphonic characteristics.

It is another object of my invention to provide an improved electrode structure for an electron discharge device which is suitable for automatic or mechanized assembly.

It is a further object to provide an improved method for constructing such an electron discharge device.

These and other objects of my invention will be ap parent from the following description taken in accordance with the accompanying drawing throughout which like reference characters indicate like parts, which drawing forms a part of this application, and in which:

Fig. 1 is a perspective view of a triode having a rectangular-shaped envelope constructed according to one embodiment of my invention;

Fig. 2 is an end view of the electrode structure of an electron discharge device constructed in accordance with one embodiment of my invention in which one end of the envelope of the electron discharge device has been cut away;

Fig. 3 is an expanded perspective view of portions of an electron discharge device constructed in accordance with my invention; and

Fig. 4 is a perspective view of an electron discharge device constructed in accordance with one embodiment of my invention in which one end of the envelope has been cut away.

In Fig. 1, there is shown a perspective view of a completed triode device using a rectangular-shaped envelope member 11. The envelope member 11 is comprised of envelope portions 13, flange portions 17 and a seal portion 15 between the flange portions 17 In this particular of my invention which is suitable for use in the automatic or mechanized assembly of electrode elements. If

- desired, one of the envelope portions 13, shown in Fig.

embodiment of my invention, heater lead members 19 1, may serve as a receptacle into which an assembly machine may place the component parts of the electrode structure in a suitable sequence. The envelope portion 13 may be provided with spacer groove portions 51 and/or spacer positioning members 53 to aid in positioning the first spacer members 29. The envelope also is provided with heater lead groove portions 59, electrode lead groove portions 61, an exhaust tubulation groove portion 63, as well as the flange portion 17. First spacer members 29 are provided with a cathode recess portion 39, grid tab recess portions 41 and anode edge recess portions 43.

During the automatic assembly process, the first spacer members 29 are positioned in the envelope portion 13 and a cathode electrode 33 having a coated portion 55 and an uncoated portion 57 is positioned in the cathode recess portion 39 of the first spacer member 29. Next, a grid electrode 35 having grid tab members 45 is positioned so that the grid tab members 45 are located in the grid tab recess portions 41. Then, second spacer members 31 are positioned, as shown, so that they rest on and are in intimate contact with the grid tab members 45 and the uncoated portion 57 of the cathode electrode 33. The second spacer members 31 are also positioned so that they are adjacent to the first spacer members 29. Then, the anode electrode 37, which includes anode tab members 49 and anode edge portions 47, is placed on top of the second spacer member 31 so that the grid electrode 35 is located between the cathode electrode 33 and the anode electrode 37. The anode electrode 37 is constructed so that it may be compressed sideways and upon expansion will lock itself in the anode edge recess portions 43 of the first spacer members 29. The anode tab members 49 are then bent downward to hold the second spacer member 31 in a locked position, thereby fixedly positioning the cathode electrode 33 and the grid electrode 35, thus preventing these electrodes from vibrating. Lead members, not shown in Fig. 2 or 3, may be previously attached to the tabs of the electrode elements and passed through the seal portion 15 of the envelope member 11. As seen in Fig. 4, all the lead members are in the same plane. If desired, an anode lead tab member 65 may be utilized, as shown in Fig. 4. A cathode heater 67 is also shown in Fig. 2. The first spacer members 29 and the second spacer members 31 over the electrode structure and the two envelope portions 13 are sealed together. In one embodiment of my invention, the sealing material may be glass solder material having a working point substantially below the softening point of the material of the envelope member 11. After a solder is applied to the flange portion 17 of the envelope portions 13, the electron discharge de vice is inserted in an oven and heated to a temperature of 450550 C. for 8l0 minutes. As soon as the solder softens, the exhaust tubulation 27 is connected to an exhaust pump and exhausted for 3 minutes until a desirable vacuum is established which, due to external atmospheric pressure, causes the two envelope portions 13 to press tightly against the soft solder resulting in a hermetic seal. The temperature is then reduced and the electron discharge device may be removed. The exhaust process is continued for 10 minutes while the metal parts are being degassed and the cathode is being activated and finally the exhaust tubulation 27 is tipped 01f. If desired during the initial heating step an inert gas, such as argon, may be injected, through the tubulation 27 to avoid' oxidation. of the metal parts of the electrode structure. It is important'that thesolder-glass usedhave a working temperature that is below the'strain point of the glass used in the envelope member, 11 'in order to avoid introducing strains in the envelope. Also, the coefficient of thermal expansion of the solder-glass must closely match thelcoefiicients of various lead members and the envelope itself. For example, I have found that a soda lime glass having a strain point of 487 C., a coefficient of thermal expansion of 92x10" per C., a working point of 1000 C. and a softening point of 696 C., is suitable for use as an envelope material with a solder glass seal material which has a softening point of 440 C. and a coefficient of thermal expansion of 84 10 per C. I have found that a material known as dumet (a copper plated alloy of 42% nickel and 58% iron) is suitable for use in the various lead members with the above materials. Another alloy suitable for use in lead members is composed of 42%nickel, 6% chromium and 52% iron. 7

Another suitable combination involves the use of envelope material of a glass having a strain point of 459 C. and a coeflicient of thermal expansion of '10l 10-' per C. A suitable solder glass seal material may have a coeflicient of thermal expansion of 101 l0' per C. and a softening point of 425 C. With these materials, suitable lead members have been made of chrome-iron alloys or of dumet. Other envelope materials'may be used, such as hard glass or ceramic materials with. suitable sealing materials.

I have also found that suitable sealing materials may include those known as epoxy resins. .These epoxy resins are glycidyl polyethers and may be prepared by reacting predetermined amounts of at least one polyhydric phenol and at least one epihalohydrin in analkaline medium. Phenols which are suitable for 'use in preparing such resinous polymeric epoxides include those which contain at least two phenolic hydroxy groups per molecule. Polynuclear phenols which have been found to be particularly suitable include those wherein the phenol nuclei are joined by carbon bridges, such for example as 4,4'-dihydroxy-diphenyl-dimethyl-methane (referred to hereinafter as bis-phenol A) and 4,4- dihydroxy-diphenyl-rnethane. In admixture with the named polynuclear phenols, use also may be made of those polynuclear phenols whereinthe'phenol nuclei are joined by sulfur bridges such, for example, as 4,4'-dihydroxy-diphenyl-sulfone.

While it is preferred to use epichlorohydrin as the epihalohydrin in the preparation of the resinous polymeric epoxide starting materials of the present invention, homologues thereof, for example, epibromohydrinand the like also may be used advantageously.

In the preparation of the resinous polymeric'epoxides, aqueous alkali is employed to combine with the halogen of the epihalohydrin reactant. The amount of alkali employed should be substantially equivalent to the amount of halogen present and preferably should be employed in an amount somewhat in excess thereof. Aqueous mixtures of alkali metal hydroxides, such as potassium hydroxide and lithium hydroxide, may be employed al-' though his preferred to use sodium hydroxide since it contained in the average molecule of the glycidyl ether. Owing to the method of preparation of the glycidyl polyethers and the fact that they are ordinarily a mixture of chemical compounds having somewhat different molecular weights and contain some compounds wherein the terminal glycidyl radicals are in hydrated form, the epoxy equivalency of the product is not necessarily the integer 2.0. However, in all cases it is a value greater than 1.0.' The 1,2-epoxy equivalency of the polyethers is thus a value between 1.0 and 2.0.

Resinous polymeric epoxides or glycidyl polyethers suitable for use in accordance with this invention may be prepared by admixing and reacting from one to two mol proportions of epihalohydrin, preferably epichlorohydrin, with about one mol proportion of bis-phenol A" in the presence of at-least a-stoichiometric excess of alkali based on the amount of halogen.

The epoxy resins may be applied to the flange portions 17 of the envelope portion 13 in the form of powder or paste. 'The material softens upon heating and the seal is formedin a manner similar to the solder glass seal described above but at a lower temperature. '-Silicone resins-have also been found to be suitable sealing materials. These resin materials have polymerization points substantially below the softening point of -the envelope material.

As shown in Fig. 3, the first spacer members 29-may be readily fixed in position by spacer positioning members 53. However, if'desired, the envelope portion 13 may be provided with spacer groove portions 51 which are suitable for positioning the first spacer members 29. If the first spacer members 29 are quite thin, the spacer positioning members 53 may prove to be more desirable as grooves less than 0.005 in. wide are diffieult tomake. Also, the first spacer members 29 mayv be positioned by a slight: surplus of the material used to seal the envelope portion 13 together in-the sealing operation.

The particular envelope member 11, shown in Figs. 1 through 4, is suitable for use in a triode, and is rectangular in general outline. However, it can be readily seen that numerous variations of design of the envelope member 11 maybe made, and envelope members adapted for use With pentode electrode structures, tWin' triode electrode structures, etc., are also feasible. These envelope members 11 may have square or circular cross sections or any desirable and suitable cross section. The envelope portions 13 shown in Figs. 1, 2 and 4 are identical which is desirable in many instances. However, non-identical envelope portions may be utilized in certain situations.

Also, the arrangement of the lead members may be varied in numerous ways. I have, found that the particular lead arrangement, shown in Figs. 1 and 4, in which the heater lead members 19 protrude from one end of the envelope member 11 and the active electrode lead members protrude from the other end of the envelope member 11, has been found to be particularly advantageous because of the reduction ofthe internal input capacitance of the electron discharge device. This is due to thefact that the coupling of the heater lead members 19 to the grid lead member 23 is practically eliminated. Also, the hum pickup by the grid lead member 23 from the heater lead members 19 is also markedly reduced.

As an example of specific sizes I have made; the dimensionsof the triode member, shown in Figs. 1 through'4, may be: length 1.5 in.; width, .in.; height, 0.62 in.; lead wire diameter, 0.022 in.; and spacing between centers of electrode leads, 0.28 in. Of course, these dimensions are merely examples, may be'changed to fit circumstances, and do not limit 'my'invention in any way.

The sealing process described in this invention may be accomplished very cheaply and eff ciently in a conveyor belt furnace containing an inert atmosphere, such .as argon, in order to prevent oxidation of the tube parts. We have also found that althoughthe exhaust tubulation 27 is usually made of glass a metallic glass tabulation can be readily utilized in my invention.

While the present invention has been shown in a few forms only, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit and scope thereof.

I claim as my invention:

1. An electron discharge device comprising an envelope member, a cathode electrode, an anode electrode, a grid electrode positioned between said cathode electrode and said anode electrode, a plurality of insulative first spacer members and a plurality of insulative second spacer members, all of the above electrodes and spacer members being within said envelope member, said first spacer members having a plurality of recess portions, portions of said cathode electrode, said grid electrode and said anode electrode being positioned in said first spacer member recess portions, said second spacer members being located adjacent to said first spacer members, portions of said anode electrode being operable to engage said second spacer members to hold said second spacer members in intimate contact with portions of said grid electrode and said cathode electrode so that said cathode electrode and said grid electrode are rigidly fixed in position.

2. An electron discharge device comprising an envelope member, a cathode electrode, an anode electrode, a grid electrode positioned between said cathode electrode and said anode electrode, a plurality of insulative first spacer members and a plurality of insulative second spacer members, all of the above electrodes and spacer members being within said envelope member, said envelope member being comprised of identical envelope portions, said envelope portions being sealed together by a seal material having a melting point substantially below the melting point of said envelope portions, said first spacer members having a plurality of recess portions, portions of said cathode electrode, said grid electrode and said anode electrode being positioned in said first spacer member recess portions, said second spacer members being located adjacent to said first spacer members, portions of said anode electrode being operable to engage said second spacer members to hold said second spacer members in intimate contact with portions of said grid electrode and said cathode electrode so that said cathode electrode and said grid electrode are rigidly fixed in position.

3. An electron discharge device comprising an envelope member, a cathode electrode, an anode electrode, a grid electrode positioned between said cathode electrode and said anode electrode, a plurality of insulative first spacer members and a plurality of insulative second spacer members, all of the above electrodes and spacer members being within said envelope member, said envelope member having a plurality of spacer groove portions, said first spacer member being positioned in said spacer groove portions, said first spacer members having a plurality of recess portions, portions of said cathode electrode, said grid electrode and said anode electrode being positioned in said first spacer member recess portions, said second spacer members being located adjacent to said first spacer members, portions of said anode electrode being operable to engage said second spacer members to hold said second spacer members in intimate contact with portions of said grid electrode and said cathode electrode so that said cathode electrode and said grid electrode are rigidly fixed in position.

4. An electron discharge device comprising an envelope member, a cathode electrode, an anode electrode, a grid electrode positioned between said cathode electrode and said anode electrode, a plurality of insulative first spacer members and a plurality of insulative second spacer members, all of the above electrodes and spacer members being within said envelope member, said envelope member having a plurality of spacer positioning members, said first spacer members being positioned by said spacer positioning members, said first spacer members having a plurality of recess'portions, portions of said cathode electrode, said grid electrode and said anode electrode being positioned in said first spacer member recess portions, said second spacer members being located adjacent to said first spacer members, portions of said anode electrode being operable to engage said second spacer members to hold said second spacer members in intimate contact with portions of said grid electrode and said cathode electrode so that said cathode electrode and said grid electrode are rigidly fixed in position.

5. An electron discharge device comprising an envelope member, a cathode electrode, an anode electrode, a grid electrode positioned between said cathode electrode and said anode electrode, a plurality of insulative first spacer members and a plurality of insulative second spacer members, all of the above electrodes and spacer members being within said envelope member, said envelope member being comprised of identical envelope portions, said envelope portions being sealed together by a seal material having a melting point substantially below the melting point of said envelope portions, said envelope member having a plurality of spacer groove portions, said first spacer members being positioned in said spacer groove portions, said envelope member having a plurality of spacer positioning members, said first spacer members being positioned by said spacer positioning members, said first spacer members having a plurality of recess portions, portions of said cathode electrode, said grid electrode and said anode electrode being positioned in said first spacer member recess portions, said second spacer members being located adjacent to said first spacer members, portions of said anode electrode being operable to engage said second spacer members to hold said second spacer members in intimate contact with portions of said grid electrode and said cathode electrode so that said cathode electrode and said grid electrode are rigidly fixed in position.

6. An electron discharge device comprising an envelope member, a plurality of insulative first spacer members, said first spacer members having a cathode recess portion, a plurality of grid tab recess portions and a plurality of anode edge recess portions, a cathode electrode positioned Within said cathode recess portion, a grid electrode having a plurality of grid tab members, an anode electrode having a plurality of anode edge members and a plurality of anode tab members, and a plurality of insulative second spacer members, all of the above electrodes and spacer members being within said envelope member, said grid electrode being positioned between said cathode electrode and said anode electrode, said grid tab members being positioned in said grid tab recess portion, said anode edge members being positioned within said anode edge recess portion so that said anode electrode is fixed in position, said second spacer members being positioned adjacent to said first spacer members, said anode tab members being operable to engage said second spacer members to hold said second spacer members in intimate contact with portions of said cathode electrode and said grid tab members so that said cathode electrode and said grid electrode are rigidly fixed in position.

References Cited in the file of this patent UNITED STATES PATENTS 1,991,174 Rose Feb. 12, 1935 2,030,187 Salzberg Feb. 11, 1936 2,225,465 Scharfnagel Dec. 17, 1940 2,406,827 Goodchild Sept. 3, 1946 2,459,487 Beggs Jan. 18, 1949 2,503,806 Diggle Apr. 11, 1950 2,731,578 McCullough Jan. 17, 1956 2,740,067 Sorg Mar. 27, 1956 

